Intumescent coating compositions may be applied on substrates, such as metal, wood, and other materials, in the manner of a coating having relatively low film thickness. Upon exposure to fire, heat or flames, the intumescent coating expands considerably in terms of thickness to produce an insulative layer of char and char foam.
That is, upon heating, the intumescent coating will produce gases and decompose to form a cellular carbonaceous char which is then expanded into foam by release of the produced gases. The foamed insulating layer of carbon protects the underlying substrate by reducing the rate of heating and hence prolongs the time for the substrate to reach critical failure temperatures. Thus, intumescent coatings are typically applied to substrates used in the construction industry to provide structures and buildings with improved fire resistance.
Not only do intumescent coatings provide fire retardancy, but they also provide performance characteristics generally expected of a conventional coating, such as fast dry times, good durability, and low cost. Incorporating both fire retardance and good coating properties in one system is not straightforward. It would, therefore, be desirable to provide improved binder compositions which may be useful in intumescent coatings, and intumescent coatings comprising these binders which demonstrate both intumescent characteristics and coating properties.